Constituent material
Main material composing an article, determining its tariff classification in many HS sections.
Constituent material refers to the main material from which an article is made, and it plays a central role in tariff classification for many HS sections. Sections VII (plastics), VIII (leather), IX (wood), X (paper), XI (textiles), XIII (ceramics/glass), and XV (metals) organise articles primarily by their manufacturing material.
The general principle is that articles of a single material are classified in the section corresponding to that material (a plastic container in Chapter 39, a glass container in Chapter 70). When an article is composed of multiple materials, the constituent material is the one predominating by weight, volume, or essential character under GIR 3b.
Important exceptions exist: articles with a specific use may be classified by function rather than material. For example, leather garments are classified in Chapter 42 (leather articles) not Chapter 41 (hides and skins), while furniture is classified in Chapter 94 regardless of material.
Determining constituent material sometimes requires laboratory analysis (chemical composition, textile fibre content, polymer identification). Results directly determine classification and therefore applicable duties, making this determination economically critical.